Primer



Patented Aug. 18, 1953 PRHVIER Martin S. Silverstein, Camden, N. J.

No Drawing. Application March 13, 1945,

Serial No. 582,482 7 1 Claim.

(Granted under Title 35, U. s.

sec. 266) v The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

The present invention relates to primers for ammunition, especially to primers for small arms ammunition, which comprise a metal cup in which an igniting charge of red phosphorus and a solid oxidizing agent for red phosphorus is contained or loaded.

Heretofore in U. S. A. patent to Pritham, Rechel, and Stevenson No. 2,194,480 granted March 26, 1940 primer compositions including red phosphorus and a solid oxidizing agent have been proposed. The primer compositions with which the present invention is concerned may be prepared as described in the said patent. By way of illustration here, a primer composition comprising an intimate mixture of of finely d1- vided red phosphorus and 80% of finely divided barium nitrate may be mentioned as a suitable composition for use in the primer cups of ammunition for igniting the propellent charges. Such a mixture may be loaded into the primer cups of ammunition in any suitable manner, or in the manner now prevalent in the art by mixing with the red phosphorus and the solid oxidizing agent an aqueous solution of a binder, such as gum tragacanth or gum arabic, so as to form a doughlike mass which is pressed into the primer cups, whereupon the other elements of the primer, usually a foil and an anvil, are inserted in succession above the composition within the cups. The primers are then subjected to a drying operation to remove water moisture from the completed primer.

Heretofore, the usual practice has been to employ primer cups composed of brass or bronze or at any event composed of a metal or alloy comprising a large proportion of copper or to employ nickel plated brass primer cups.

Now I have discovered that primer cups composed of copper or of a metal or alloy comprising a large proportion of copper and nickel plated primer cups cause the above described red phosphorus primer compositions within the cups to deteriorate on storage or on being kept for a period of time, and that after the lapse of time the primers become less sensitive to such a degree as to render them unreliable for use. This, I have found, is due to the fact that the primer composition containing red phosphorus makes contact with the metal of the primer cup which presents a metallic surface containing a large proportion of copper or nickel in direct contact with Code (1952),

the igniting composition. The presence of a surface containing a large proportion of nickel or copper in direct contact with a priming composition comprising red phosphorus and a solid oxidizing agent, such as barium nitrate, basic lead nitrate, lead peroxide and the like, causes an acceleration of the rate of oxidation of the red phosphorus in the primer, either as the result of oxygen and moisture taken up from the ambient atmosphere or as the result of oxygen derived from thesolid oxidizing agent contained within the priming composition, or as a result of both of these sources of oxygen. The oxidation of the red phosphorus in the composition results in the formation of acids of phosphorus which are of a hydroscopic nature and tend to form liquids, and after atime these acids permeate the composition in the cup, dissolve copper or films of copper oxide from the cups and carry dissolved copper salts into the body of the primer composition. These copper salts so brought into the primer composition act as accelerators of oxidation of the red phosphorus, and this accelerated oxidation results in the disadvantages 'previously mentioned.

As a result of the above discoveries I have found that primer cups composed of metals that are catalytically less active than pure nickel in the oxidation of red phosphorus overcome the objections described above. Pure copper has much greater catalytic activity than nickel, and cartridge brass is slightly less active than pure nickel. Thus, for example, primer cups composed of aluminum, aluminum alloys (e. g. 50% Al, 50% Mg) or Duralumin may be used in overcoming the above described disadvantages.

Further, I have found that it is not necessary that the whole body of the primer cup be composed of a metal that is less catalytically active than nickel in increasing or accelerating the rate of oxidation of red phosphorus, for I have found that it is sufiicient to coat over, as for example by electroplating, brass or bronze or other metal primer cups with a metal or metallic coating which is less active catalytically than nickel in causing increase in rate of oxidation of red phosphorus. Thus, for example, primer cups composed of brass may .be coated with zinc or aluminum, both within and without the cups, but necessarily within the cup, by making use of any suitable metal coating process. Similarly, brass cups may be chromium or cadmium plated; and also lead and tin, or alloys of lead and tin may be coated on brass primer cups by tinning operations utilizing a flux. Lead and tin, or alloys thereof, in the molten condition, in the presence of a flux, coat over heated brass very easily, as is well known in the soldering of brass parts.

It is common practice to place a paper or metal foil between the primer composition in the cup and the anvil of the primer, whereby the metal of the anvil is at least initially out of direct physical contact with the red phosphorus composition. Notwithstanding this prac tice, problems have arisen for it has been repeatedly observed that the anvil pierced the foil, whereby the anvil comes into direct contact with the red phosphorus priming compositions and catalytic effects, as above described, may arise. In order to overcome this objection, the anvils may be made of the same materials described above for the primer cups of the present invention, or may be made of brass or other cataly tically active materials coated over with a ma terial less catalytically active than pure nickel as regards the oxidation of red phosphorus. Also in instances where much moisture is contained in the ambient atmosphere Where the cartridges containing the primers are used, kept or stored, it may well occur that the creeping and hygroscopic characteristics of the acids of phosphorus will cause these liquid acids to reach the anvils, :and if they were not also formed or coated according to the present invention, copper or a similarly active catalyst for the oxidation of red phosphorus would be introduced into the priming compositionby portions of the anvils dissolving in the acids of phosphorus. :the 'anvils may be formed wholly of aluminum, Duraluinin aluminum magnesium alloy, or may consist of a base of brass or other metal coated with zinc, cadmium, chromium, or aluminum.

In the presence of a priming composition including red phosphorus and a solid oxidizing said components.

datalytically less active than pure nickel in increasing the rate of oxidation of red phosphorus. Among the metals that accelerate the rate of oxidation of red phosphorus in the priming compositions more than nickel, may be mentioned copper, silver, iron and bismuth.

I claim:

In a primer, the combination of a primer composition comprising red phosphorus and a solid oxidizing agent for red phosphorus and primer housing components presenting a metallic surface of zinc to said composition where said'coinpositio'n makes direct contact with the MARTIN S. SILVERSTEIN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,068,516 Seavey Jan. 19, '193'7 2,125,356 Noddin Aug. 2, 1938 2,194,480 Pritham Mar. 26, 1940 2,255,600 Salzberg 2 Sept. 9, '1941 FGREIGN PATENTS Number Country Date 274,000 Germany May 1 2, 1914 508,244 Germany Sept. 11, 1930 401,843 Great Britain Nov. 23, 1933 432,395 Great Britain July 25, 1935 

